Functionalized polymer and rubber compositions produced from solubilized anionic polymerization initiators

ABSTRACT

The present invention is directed toward anionic polymerization initiators which are soluble in acyclic alkane solvents. The initiators include a solubilized lithio amine having the general formula (A)Li(SOL) y . SOL is a solubilizing component and A is an alkyl, dialkyl or cycloalkyl amine radical or a cyclic amine and y is from about 1 to 4. The cyclic amine has an alkylene, oxy- or amino-alkylene group having from about 3 to about 16 methylene groups. The invention is also directed toward polymers and other products made using the initiator, and methods therefor. Further, the invention contemplates a polymer, a polymer composition and products therefrom, which include a functional group from the reaction product of an amine and an organolithium compound. The resulting polymers may be terminated with a terminating, coupling or linking agent, which may provide the polymer wtih a multifunctionality.

RELATED APPLICATION

This Application is a Divisional Application of pending U.S. patentapplication Ser. No. 08/065,791, filed May 24, 1993, which is aContinuation-in-Part of U.S. patent application Ser. No. 07/955,969,filed Oct. 2, 1992, now U.S. Pat. No. 5,332,810.

TECHNICAL FIELD

The subject invention relates to anionic polymerizations resulting indiene polymer and copolymer elastomers. More particularly, the presentinvention relates to polymerization employing a solubilized amineinitiator. Specifically, the invention relates to a solubilized lithiumamine initiator which is soluble in acyclic alkane solvents, and whichwill reproducibly polymerize monomers in a controllable and narrowmolecular weight distribution range.

BACKGROUND ART

When conducting polymerizations on a commercial basis, it is importantto utilize process conditions and components which will allow themolecular weight of the end products to be narrowly and reproduciblydefined. The characteristics of a given polymer and its usefulness aredependent, among other things, upon its molecular weight. Hence, it isdesirable to be able to predict with some certainty the molecular weightof the end product of the polymerization. When the molecular weight isnot narrowly definable, or is not reproducible on a systematic basis,the process is not commercially viable.

In the art, it is desirable to produce elastomeric compounds exhibitingreduced hysteresis characteristics. Such elastomers, when compounded toform articles such as tires, power belts and the like, will show anincrease in rebound, a decrease in rolling resistance and will have lessheat build-up when mechanical stresses are applied.

A major source of hysteretic power loss has been established to be dueto the section of the polymer chain from the last cross link of thevulcanizate to the end of the polymer chain. This free end cannot beinvolved in an efficient elastically recoverable process, and as aresult, any energy transmitted to this section of the cured sample islost as heat. It is known in the art that this type of mechanism can bereduced by preparing higher molecular weight polymers which will havefewer end groups. However, this procedure is not useful becauseprocessability of the rubber with compounding ingredients and duringshaping operations decreases rapidly with increasing molecular weight.

It is difficult to obtain consistent properties, such as a reduction inhysteresis properties, if the polymer cannot be controllably reproducedin a narrow molecular weight range distribution. See, for example, U.S.Pat. No. 4,935,471, in which some polymers are prepared with aheterogeneous mixture of certain secondary amines, including lithiumpyrrolidide. Polymers made in this manner have widely variable molecularweights, broad polydispersities, and their functional terminations tendto reproduce erratically, giving rise to poorly reproducible hysteresisreduction results.

A major drawback with many of these known initiators, is that they arenot soluble in acyclic alkanes, such as hexane. Polar solvents haveheretofore been employed including the polar organic ethers such asdimethyl or diethyl ether, tetrahydrofuran, tetramethylethylenediamine,or diethylene glycol methyl ether (diglyme).

The present invention provides novel initiators for anionicpolymerization, which are soluble in acyclic alkanes. The inventionprovides for the incorporation of a functionality from the initiator tobe incorporated at the head and tail of the polymer chain. The inventionprovides for efficient, controllable and reproducible polymerizations,with the preparation of well defined end-products of a relatively narrowmolecular weight range distribution.

DISCLOSURE OF THE INVENTION

It is therefore, an object of the present invention to provide ananionic polymerization initiator which is soluble in acyclic alkanes.

It is a further object of the present invention to provide a method ofpreparing such an anionic polymerization initiator.

It is still a further object of the invention to provide an initiatorwhich will reproducibly result in a polymer within a narrow, predictablemolecular weight range.

It is another object of the present invention to provide elastomersformed with such a polymerization initiator.

It is also an object of certain embodiments of the present invention toprovide diene polymers and copolymers having reduced hysteresischaracteristics.

It is a further object of the present invention to provide vulcanizableelastomeric compounds of diene polymers and copolymers having reducedhysteresis characteristics.

Still another object of the present invention is to provide an improvedtire formed from an elastomer as described hereinabove.

At least one or more of these objects together with the advantagesthereof over the existing art, which shall become apparent from thespecification which follows, are accomplished by the invention ashereinafter described and claimed.

In general, according to the present invention, an anionicpolymerization initiator which is soluble in acyclic alkane solvents,comprises a solubilized lithio amine having the general formula

    (A)Li(SOL).sub.y

where y is from about 1 to about 3; SOL is a solubilizing componentselected from the group consisting of hydrocarbons, ethers, amines ormixtures thereof; and, A is selected from the group consisting of alkyl,dialkyl and cycloalkyl amine radicals having the general formula##STR1## and cyclic amines having the general formula ##STR2## where R₁is selected from the group consisting of alkyls, cycloalkyls or aralkylshaving from 1 to about 12 carbon atoms, and R₂ is selected from thegroup consisting of an alkylene, oxy- or amino-alkylene group havingfrom about 3 to about 16 methylene groups.

There is also provided a method of preparing an anionic polymerizationinitiator, which method comprises the steps of reacting an organolithiumcompound with a functionalizing agent in the presence of a solubilizingagent; the functionalizing agent being selected from the groupconsisting of alkyl, dialkyl and cycloalkyl amine radicals having thegeneral formula ##STR3## and cyclic amines having the general formula##STR4## where R₁ is selected from the group consisting of alkyls,cycloalkyls or aralkyls having from 1 to about 12 carbon atoms, and R₂is selected from the group consisting of an alkylene, oxy- oramino-alkylene group having from about 3 to about 16 methylene groups;and, the solubilizing agent is selected from the group consisting ofhydrocarbons, ethers, amines or mixtures thereof.

A method of preparing an anionic polymerization initiator comprises thesteps of reacting an organolithium compound with a functionalizing agentto form a reaction product. The functionalizing agent is selected fromthe group consisting of alkyl, dialkyl and cycloalkyl amine radicalshaving the general formula ##STR5## and cyclic amines having the generalformula ##STR6## where R₁ is selected from the group consisting ofalkyls, cycloalkyls or aralkyls having from 1 to about 12 carbon atoms,and R₂ is selected from the group consisting of an alkylene, oxy- oramino-alkylene group having from about 3 to about 16 methylene groups.The method also comprises the step of reacting the reaction product witha solubilizing agent selected from the group consisting of hydrocarbons,ethers, amines or mixtures thereof.

A functionalized polymer comprises a polymer chain carrying at least onefunctional group A wherein A is derived from a polymerization initiatorhaving the general formula

    (A)Li(SOL).sub.y

where y is of from about 1 to about 3; SOL is a solubilizing componentselected from the group consisting of hydrocarbons, ethers, amines ormixtures thereof; and, A is selected from the group consisting of alkyl,dialkyl and cycloalkyl amine radicals having the general formula##STR7## and cyclic amines having the general formula ##STR8## where R₁is selected from the group consisting of alkyls, cycloalkyls or aralkylshaving from 1 to about 12 carbon atoms, and R₂ is selected from thegroup consisting of an alkylene, oxy-or amino-alkylene group having fromabout 3 to about 16 methylene groups.

A method of forming a functionalized polymer, according to theinvention, comprises the steps of forming a solution of one or moreanionically polymerizable monomers in an alkane solvent; and,polymerizing the monomers in the presence of an initiator which issoluble in the alkane solvent. The initiator comprises a solubilizedlithio amine having the general formula

    (A)Li(SOL).sub.y

where y is from about 1 to about 3; SOL is a solubilizing componentselected from the group consisting of hydrocarbons, ethers, amines ormixtures thereof; and, A is selected from the group consisting of alkyl,dialkyl and cycloalkyl amine radicals having the general formula##STR9## and cyclic amines having the general formula ##STR10## where R₁is selected from the group consisting of alkyls, cycloalkyls or aralkylshaving from 1 to about 12 carbon atoms, and R₂ is selected from thegroup consisting of an alkylene, oxy- or amino-alkylene group havingfrom about 3 to about 16 methylene groups.

A vulcanizable elastomeric compound having reduced hysteresis propertiescomprises an elastomeric polymer having chains carrying at least onefunctional group A, wherein A is derived from a polymerization initiatorhaving the general formula

    (A)Li(SOL).sub.y

where y is of from about 1 to about 3; SOL is a solubilizing componentselected from the group consisting of hydrocarbons, ethers, amines ormixtures thereof; and, A is selected from the group consisting of alkyl,dialkyl and cycloalkyl amine radicals having the general formula##STR11## and cyclic amines having the general formula ##STR12## whereR₁ is selected from the group consisting of alkyls, cycloalkyls oraralkyls having from 1 to about 12 carbon atoms, and R₂ is selected fromthe group consisting of an alkylene, oxy- or amino-alkylene group havingfrom about 3 to about 16 methylene groups; and from about 5 to 80 partsby weight of carbon black, per 100 parts of the polymer.

The present invention also provides a tire having decreased rollingresistance resulting from a treadstock containing a vulcanizableelastomeric composition which comprises an elastomeric polymer havingchains carrying at least one functional group A wherein A is derivedfrom a polymerization initiator having the general formula

    (A)Li(SOL).sub.y

where y is of from about 1 to about 3; SOL is a solubilizing componentselected from the group consisting of hydrocarbons, ethers, amines ormixtures thereof; and, A is selected from the group consisting of alkyl,dialkyl and cycloalkyl amine radicals having the general formula##STR13## and cyclic amines having the general formula ##STR14## whereR₁ is selected from the group consisting of alkyls, cycloalkyls oraralkyls having from 1 to about 12 carbon atoms, and R₂ is selected fromthe group consisting of an alkylene, oxy- or amino-alkylene group havingfrom about 3 to about 16 methylene groups; and from about 5 to 80 partsby weight of carbon black, per 100 parts by weight of said polymer.

A vulcanizable rubber composition comprises a polymer carrying at leastone amine functional group A, wherein A is derived from the reactionproduct of an organolithium compound and an amine; and a tin-carbonbond.

A multifunctional polymer comprises at least one functional group A,wherein A is derived from the reaction product of an organolithiumcompound and an amine; and, a tin-carbon bond.

A vulcanizable rubber composition comprises a polymer carrying at leastone amine functional group A, wherein A is derived from the reactionproduct of an organolithium compound and an amine; and a secondfunctional group selected and derived from the group consisting ofterminating agents, coupling agents and linking agents.

A tire having at least one vulcanizable elastomeric component comprisesa multifunctional polymer having at least one functional group A,wherein A is derived from a polymerization initiator which is thereaction product of an organolithium compound and an amine, wherein themultifunctional polymer has a tin-carbon bond, and from about 5 to 80parts by weight of carbon black, per 100 parts of the polymer.

A multifunctional polymer comprises at least one functional group A,wherein A is derived from the reaction product of an organolithiumcompound and an amine; and a second functional group selected andderived from the group consisting of terminating agents, coupling agentsand linking agents.

A tire having at least one vulcanizable elastomeric component is alsoprovided, which component comprises a multifunctional polymer having atleast one functional group A, wherein A is derived from a polymerizationinitiator which is the reaction product of an organolithium compound andan amine; the polymer having a second functional group selected andderived from the group consisting of terminating agents, coupling agentsand linking agents; and from about 5 to 80 parts by weight of carbonblack, per 100 parts of said polymer.

PREFERRED EMBODIMENT FOR CARRYING OUT THE INVENTION

As will become apparent from the description which follows, the presentinvention provides novel polymerization initiators which are soluble inacyclic alkanes, including normal alkanes such as hexane, pentane,heptane, isoheptane, octane, their alkylated derivatives, mixturesthereof, and the like. It has also been discovered herein that certainrubber compositions, vulcanizable elastomeric compositions and articlesthereof based upon polymers formed using such initiators, exhibit usefulproperties, such as for example, reproducible relatively narrowmolecular weight ranges. Furthermore, the polymers according to theinvention also contain a functionality from the initiator, whichfunctionality is useful for example, in reducing hysteresis properties.

While the initiators of the present invention are soluble in acyclicalkane solvents, it will be appreciated that the use of the initiatorsin other solvents is also within the scope of the invention.

The preferred initiator according to the invention, is the reactionproduct of an amine, an organo lithium and a solubilizing component. Theorgano lithium and the amine may be reacted in the presence of thesolubilizing component or agent, or they may be reacted first and thereaction product thereof subsequently treated with the solubilizingcomponent. The preferred initiator is therefore, a solubilized lithioamine having the general formula

    (A)Li(SOL).sub.y

where y is from about 1 to about 3. The parentheses of this generalformula connote that the formula may include A-Li-SOL_(y) ; SOL_(y)-A-Li; or, A-SOL_(y) -Li.

(SOL) is a solubilizing component and may be a hydrocarbon, ether, amineor a mixture thereof. It has been discovered that by the presence of the(SOL) component, the initiator is soluble in acyclic alkanes.

Exemplary (SOL) groups include dienyl or vinyl aromatic polymers orcopolymers having from 3 to about 300 polymerization units. Suchpolymers include polybutadiene, polystyrene, polyisoprene and copolymersthereof. Other examples of (SOL) include polar ligands, such astetrahydrofuran (THF) and tetramethylethylenediamine (TMEDA).

The (A) component represents the amine functionality, at least one ofwhich is carried by the resulting polymer, such as by being incorporatedat the initiation site or head thereof. For example, (A) may be adialkyl or dicycloalkyl amine radical having the general formula##STR15## or a cyclic amine having the general formula ##STR16## Inthese formulas, R₁ is an alkyl, cycloalkyl or aralkyl having from 1 toabout 20 carbon atoms, where both R₁ groups may be the same ordifferent, and R₂ is an alkylene, oxy- or amino-alkylene group havingfrom about 3 to about 16 methylene groups.

Exemplary R₁ groups include methyl, ethyl, butyl, octyl, cyclohexyl,3-phenyl-1-propyl, isobutyl and the like. Exemplary R₂ groups includetetramethylene, hexamethylene, oxydiethylene, N-alkylazadiethylene,dodecamethylene, hexadecamethylene and the like.

For example, (A) may be derivative of pyrrolidine; piperidine;piperazine; perhydroazepine, also known as hexamethyleneimine;1-azacyclooctane; azacyclotridecane, also known as dodecamethyleneimine;azacycloheptadecane, also known as hexadecamethyleneimine;1-azacycloheptadec-9-ene; or, 1-azacycloheptadec-8-ene; includingbicyclics such as perhydroisoquinoline, perhydroindole, and the like.Pyrrolidine, perhydroazepine and 1-azacyclooctane are preferred. Twopreferred pyrrolidine derivatives include perhydroindole andperhydroisoquinoline.

It has been found that when R₁ or R₂ are a di-t-butyl group, adiisopropyl group or the like, the resulting polymerizations are slow,presumably due to hinderence around the nitrogen at the initiation site.Hence, in a preferred embodiment of the invention, the carbon atoms inR₁ and R₂ which are bonded to the nitrogen in the amine, are also bondedto a total of at least three hydrogen atoms.

The initiator according to the present invention can be formed bypreparing a solution of the amine component (A), in an anhydrous,aprotic solvent, such as hexane, preferably in the presence of thesolubilizing agent or component (SOL), if (SOL) is an ether or an aminocompound. To this solution is then added an organolithium catalyst inthe same or a similar solvent. The organolithium compound has thegeneral formula RLi where R is selected front the group consisting ofalkyls, cycloalkyls, alkenyls, aryls and aralkyls having from 1 to about20 carbon atoms and short chain length low molecular weight polymersfrom diolefin and vinyl aryl monomers having up to about 25 units.Typical alkyls include n-butyl, s-butyl, methyl, ethyl, isopropyl andthe like. The cycloalkyls include cyclohexyl, menthyl and the like. Thealkenyls include allyl, vinyl and the like. The aryl and aralkyl groupsinclude phenyl, benzyl, oligo(styryl) and the like. Exemplary shortchain length polymers include the oligo(butadienyls), oligo(isoprenyls),oligo(styryls) and the like.

If (SOL) is a short chain length polymer, the monomers to used to form(SOL) are added after the the amine and the organolithium are mixed, aswill be addressed hereinbelow.

To the solution of the amine and the organolithium, is added a solutionof the monomers of the solubilizing component (SOL) in the same orsimilar solvent, if (SOL) is a polydiene or a polyvinyl aromatic. Thethree components are allowed to react for up to about one hour atambient temperature (25° to 30° C.), or elevated temperatures up toabout 100° C. preferably at less than 50° C., and more preferably atless than 38° C., following which the catalyst is ready for use. Theinitiators according to the present invention are considered to besoluble if they remain in solution within an excess of an acyclic alkanesolvent for about 3 or more days.

As stated above, the initiator thus formed may be employed as aninitiator to prepare any anionically-polymerized elastomer, e.g.,polybutadiene, polyisoprene and the like, and copolymers thereof withmonovinyl aromatics such as styrene, alpha methyl styrene and the like,or trienes such as myrcene. Thus, the elastomers include dienehomopolymers and copolymers thereof with monovinyl aromatic polymers.Suitable monomers include conjugated dienes having from about 4 to about12 carbon atoms and monovinyl aromatic monomers having 8 to 18 carbonatoms and trienes. Examples of conjugated diene monomers and the likeuseful in the present invention include 1,3-butadiene, isoprene,1,3-pentadiene, 2,3-dimethyl- 1,3-butadiene and 1,3-hexadiene, andaromatic vinyl monomers include styrene, a-methylstyrene,p-methylstyrene, vinyltoluene and vinylnaphthalene. The conjugated dienemonomer and aromatic vinyl monomer are normally used at the weightratios of 95-50:5-50, preferably 95-65:5-35.

Polymerization is conducted in an acyclic alkane solvent, such as thevarious hexanes, heptanes, octanes, mixtures thereof, and the like. Inorder to promote randomization in copolymerization and to control vinylcontent, a polar coordinator may be added to the polymerizationingredients. Amounts range between 0 and 90 or more equivalents perequivalent of lithium. The amount depends on the amount of vinyldesired, the level of styrene employed and the temperature of thepolymerization, as well as the nature of the specific polar coordinator(modifier) employed.

Compounds useful as polar coordinators are organic and includetetrahydrofuran (THF), linear and cyclic oligomeric oxolanyl alkanessuch as 2-2'-di(tetrahydrofuryl) propane, di-piperidyl ethane,hexamethylphosphoramide, N-N'-dimethylpiperazine, diazabicyclooctane,dimethyl ether, diethyl ether, tributylamine and the like. The linearand cyclic oligomeric oxolanyl alkane modifiers are described in U.S.Pat. No. 4,429,091, owned by the Assignee of record, the subject matterof which is incorporated herein by reference. Compounds useful as polarcoordinators include those having an oxygen or nitrogen hetero-atom anda non-bonded pair of electrons. Other examples include dialkyl ethers ofmono and oligo alkylene glycols; "crown" ethers; tertiary amines such astetramethylethylene diamine (TMEDA); linear THF oligomers and the like.

A batch polymerization is usually begun by charging a blend ofmonomer(s) and an acyclic alkane solvent to a suitable reaction vessel,followed by the addition of the polar coordinator (if employed) and theinitiator compound previously described. The reactants are heated to atemperature of from about 20° to about 200° C., and the polymerizationis allowed to proceed for from about 0.1 to about 24 hours. A functionalamine group is derived from the initiator compound and attaches at theinitiation site. Thus, substantially every resulting polymer chain hasthe following general formula

    AYLi

where A is as described above, and Y is a divalent polymer radical whichis derived from any of the foregoing diene homopolymers, monovinylaromatic polymers, diene/monovinyl aromatic random copolymers and blockcopolymers. The monomer addition at the lithium end causes the molecularweight of the polymer to increase as the polymerization continues.

To terminate the polymerization, and thus further control polymermolecular weight, a terminating agent, coupling agent or linking agentmay be employed, all of these agents being collectively referred toherein as "terminating agents". Certain of these agents may provide theresulting polymer with a multifunctionality. That is, the polymersinitiated according to the present invention, may carry at least oneamine functional group A as discussed hereinabove, and may also carry asecond functional group selected and derived from the group consistingof terminating agents, coupling agents and linking agents.

Useful terminating, coupling or linking agents include active hydrogencompounds such as water or alcohol; carbon dioxide;N,N,N',N'-tetradialkyldiaminobenzophenone (such astetramethyldiaminobenzophenone or the like);N,N-dialkylaminobenzaldehyde (such as dimethylaminobenzaldehyde or thelike); 1,3-dialkyl-2-imidazolidinones (such as1,3-dimethyl-2-imidazolidinone or the like); 1-alkyl substitutedpyrrolidinones; 1-aryl substituted pyrrolidinones; dialkyl- anddicycloalkyl-carbodiimides having from about 5 to about 20 carbon atoms;(R₃)_(a) ZX_(b) ; ##STR17## where Z is tin or silicon. It is preferredthat Z is tin.

R₃ is an alkyl having from about 1 to about 20 carbon atoms; acycloalkyl having from about 3 to about 20 carbon atoms; an aryl havingfrom about 6 to about 20 carbon atoms; or, an aralkyl having from about7 to about 20 carbon atoms. For example, R₃ may include methyl, ethyl,n-butyl, neophyl, phenyl, cyclohexyl or the like.

X is chlorine or bromine, "a" is from 0 to 3, and "b" is from about 1 to4, where a+b=4.

Each R₄ is the same or different and is an alkyl, cycloalkyl or aryl,having from about 1 to about 12 carbon atoms. For example, R₄ mayinclude methyl, ethyl, nonyl, t-butyl, phenyl or the like.

R₅ is an alkyl, phenyl, alkylphenyl or N,N-dialkylaminophenyl, havingfrom about 1 to about 20 carbon atoms. For example, R₅ may includet-butyl, 2-methyl-4-pentene-2-yl, phenyl, p-tolyl, p-butylphenyl,p-dodecylphenyl, p-diethylaminophenyl, p-(pyrrolidino)phenyl, and thelike.

Each R₆ is the same or different, and is an alkyl or cycloalkyl havingfrom about 1 to about 12 carbon atoms. Two of the R₆ groups may togetherform a cyclic group. For example, R₆ may include methyl, ethyl, octyl,tetramethylene, pentamethylene, cyclohexyl or the like.

R₇ may include alkyls, phenyls, alkylphenyls or N,N-dialkylaminophenyls,having from about 1 to about 20 carbon atoms. For example, R₇ mayinclude methyl, butyl, phenyl, p-butylphenyl, p-nonylphenyl,p-dimethylaminophenyl, p-diethylaminophenyl, p-(piperidino)phenyl, orthe like.

Other examples of useful terminating agents include tin tetrachloride,(R₁)₃ SnCl, (R₁)₂ SnCl₂, R₁ SnCl₃, carbodiimides, N-methylpyrrolidine,cyclic amides, cyclic ureas, isocyanates, Schiff bases,4,4'-bis(diethylamino) benzophenone, and the like, where R₁ is asdescribed hereinabove.

One preferred polymer according to the present invention, is a polymerwhich includes at least one functional group A as discussed hereinabove,wherein A is derived from the reaction product of an amine and anorganolithium compound as also discussed hereinabove. Furthermore, apreferred polymer is multifunctional wherein the polymer also carries atin-carbon bond, such as may be derived from the terminating, couplingor linking agent. A rubber composition or a vulcanizable rubbercomposition according to the present invention, may include such apolymer.

The terminating, coupling or linking agent is, added to the reactionvessel, and the vessel is agitated for about 1 to about 1000 minutes. Asa result, an elastomer is produced having an even greater affinity forcompounding materials such as carbon black, and hence, even furtherreduced hysteresis. Additional examples of terminating agents includethose found in U.S. Pat. No. 4,616,069 which is herein incorporated byreference.

The polymer may be separated from the solvent by conventionaltechniques. These include steam or alcohol coagulation, thermaldesolventization, or any other suitable method. Additionally, solventmay be removed from the resulting polymer by drum drying, extruderdrying, vacuum drying or the like.

The elastomers of the present invention comprise a plurality ofpolymers, having a functional group at both the head and tail of theresulting polymer. Such compounding may result in products exhibitingreduced hysteresis, which means a product having increased rebound,decreased rolling resistance and has less heat build-up when subjectedto mechanical stress.

It has also been found, as will be exemplified hereinbelow, thatpolymers formed using the initiators of the invention, are reproduciblyformable in a relatively narrow range of molecular weights, such thatsubstantially consistently reproducible polymers are possible with amolecular weight range of about 20,000 to about 250,000.

The polymers of the present invention can be used alone or incombination with other elastomers to prepare a product such as a tiretreadstock, sidewall stock or other tire component stock compound. Atleast one such component is produced from a vulcanizable elastomeric orrubber composition. For example, the polymers according to the inventioncan be blended with any conventionally employed treadstock rubber whichincludes natural rubber, synthetic rubber and blends thereof. Suchrubbers are well known to those skilled in the art and include syntheticpolyisoprene rubber, styrene/butadiene rubber (SBR), polybutadiene,butyl rubber, Neoprene, ethylene/propylene rubber,ethylene/propylene/diene rubber (EPDM), acrylonitrile/butadiene rubber(NBR), silicone rubber, the fluoroelastomers, ethylene acrylic rubber,ethylene vinyl acetate copolymer (EVA), epichlorohydrin rubbers,chlorinated polyethylene rubbers, chlorosulfonated polyethylene rubbers,hydrogenated nitrile rubber, tetrafluoroethylene/propylene rubber andthe like. When the polymers of the present invention are blended withconventional rubbers, the amounts can vary widely such as between 10 and99 percent by weight.

The polymers can be compounded with carbon black in amounts ranging fromabout 5 to about 100 parts by weight, per 100 parts of rubber (phr),with about 5 to about 80 parts being preferred and from about 40 toabout 70 phr being more preferred. The carbon blacks may include any ofthe commonly available, commercially-produced carbon blacks but thosehaving a surface area (EMSA) of at least 20 m² /g and more preferably atleast 35 m² /g up to 200 m² /g or higher are preferred. Surface areavalues used in this application are those determined by ASTM test D-1765using the cetyltrimethyl-ammonium bromide (CTAB) technique. Among theuseful carbon blacks are furnace black, channel blacks and lamp blacks.More specifically, examples of the carbon blacks include super abrasionfurnace (SAF) blacks, high abrasion furnace (HAF) blacks, fast extrusionfurnace (FEF) blacks, fine furnace (FF) blacks, intermediate superabrasion furnace (ISAF) blacks, semi-reinforcing furnace (SRF) blacks,medium processing channel blacks, hard processing channel blacks andconducting channel blacks. Other carbon blacks which may be utilizedinclude acetylene blacks. Mixtures of two or more of the above blackscan be used in preparing the carbon black products of the invention.Typical values for surface areas of usable carbon blacks are summarizedin the following TABLE I.

                  TABLE I                                                         ______________________________________                                        CARBON BLACKS                                                                 ASTM           Surface Area                                                   Designation    (m.sup.2 /g)                                                   (D-1765-82a)   (D-3765)                                                       ______________________________________                                        N-110          126                                                            N-220          111                                                            N-339          95                                                             N-330          83                                                             N-550          42                                                             N-660          35                                                             ______________________________________                                    

The carbon blacks utilized in the preparation of the rubber compounds ofthe invention may be in pelletized form or an unpelletized flocculentmass. Preferably, for more uniform mixing, unpelletized carbon black ispreferred. The reinforced rubber compounds can be cured in aconventional manner with known vulcanizing agents at about 0.5 to about4 phr. For example, sulfur or peroxide-based curing systems may beemployed. For a general disclosure of suitable vulcanizing agents onecan refer to Kirk-Othmer, Encyclopedia of Chemical Technology, 3rd ed.,Wiley Interscience, N.Y. 2, Vol. 20, pp. 365-468, particularly"Vulcanization Agents and Auxiliary Materials" pp. 390-402. Vulcanizingagents may be used alone or in combination.

Vulcanizable elastomeric or rubber compositions of the invention can beprepared by compounding or mixing the polymers thereof with carbon blackand other conventional rubber additives such as fillers, plasticizers,antioxidants, curing agents and the like, using standard rubber mixingequipment and procedures and conventional amounts of such additives.

General Experimental

In order to demonstrate the preparation and properties of the initiatorsand elastomers according to the present invention, a number of suchinitiators and elastomers were prepared. A solution of styrene andbutadiene monomers in hexane was prepared and was polymerized with theabove described initiators. To further show the effectiveness of theinvention, a number of similar monomer solutions were polymerized with aheterogenous mixture of non-solubilized lithium pyrrolidide as aninitiator to provide comparative control examples. The non-solubilizedlithium pyrrolidides will be discussed first hereinbelow, followed byexamples of initiators and elastomers made according to the presentinvention. As noted above, various techniques known in the art forcarrying out polymerizations may be employed without departing from thescope of the present invention.

I. Non-Solubilized Lithium Pyrrolidide Initiation

The following examples are included for comparison to the initiators andelastomers prepared according to the invention, which will beexemplified hereinbelow.

Experiment No. 1

Initiator Preparation

In a small dried and nitrogen purged bottle, 20 ml of a 0.5M solution ofpyrrolidine in hexanes (10 milliequivalent or "meq") was treated with6.36 ml of a 1.65M solution of n-butyllithium in hexanes (10.5 meq). Thebottle was fitted with a perforated crown seal having a rubber liner.The resulting heterogeneous mixture was agitated gently at roomtemperature for 16 hours, after which the product was drawn off for useas an initiator. The mixture was shaken vigorously before and whiledrawing off the samples.

Polymerization

The initiator mixture made in the above manner was transferred bysyringe to each of two small bottles which were also fitted with a sealas above. The bottles each contained a 75/25 weight percent monomerblend of butadiene/styrene, at 25 weight percent in hexane and a levelof 1.0 meq Li/100 grams of monomer. The bottles also contained 0.6 toolof N,N,N',N'-tetramethylethylenediamine (TMEDA) per mol of lithium. Themixtures were agitated at 50° C. for 2.5 hours. The reaction resulted inapproximately 100 percent conversion of monomer to polymer.

The first bottle of cement, EXAMPLE 1, was then quenched by injection of1.5 milliliters (ml) of isopropyl alcohol (i-PrOH), and the secondbottle of cement, EXAMPLE 2, was treated for an additional 90 minutes at50° C. with 1.15 mol of 4-(N,N-diethylamino) benzaldehyde per mol oflithium. The cement of EXAMPLE 2 was then quenched with 1.5 ml ofi-PrOH.

Both cements from EXAMPLE 1 and EXAMPLE 2 were treated with anantioxidant, namely, 2 ml of a mixture containing 2.0 weight percent ofdibutyl paracresol (DBPC) and 0.7 weight percent of UOP-88, availablefrom Universal Oil Products Co., in hexane. The cements were thencoagulated in i-PrOH and drum dried. The resulting polymers wereanalyzed, and the characteristics thereof are reported in TABLE IIhereinbelow.

                  TABLE II                                                        ______________________________________                                        ANALYSIS OF POLYMERS FROM EXAMPLES 1 AND 2                                               Example I   Example 2                                              ______________________________________                                        HNMR         24% styrene   24.8% styrene                                                   (0% block styrene)                                                                          (0% block styrene)                                 Percent of butadiene                                                                       51.9%         49.4%                                              portion as 1,2 linkages                                                       GPC (THF solvent)                                                             Mn           136365        136697                                             Mw/Mn        1.35          1.40                                               Tg.sup.a     -36.5° C.                                                                            -38.8° C.                                   ______________________________________                                         .sup.a glass transition temperature at onset                             

The polymers of EXAMPLES 1 and 2 were compounded using the rubber recipereported in TABLE III hereinbelow.

                  TABLE III                                                       ______________________________________                                        COMPOUNDING RECIPE                                                                        Mix     Parts per Hundred                                         Ingredient  Order   Parts Rubber                                              ______________________________________                                        Polymer     1       100           Masterbatch                                 Naphthenic oil                                                                            2       10            145-155° C.,                         Carbon black,                                                                             3       55            60 RPM                                      N-351                                                                         ZnO         4       3                                                         Antioxidant 5       1                                                         Wax blend   6       2                                                         Total Masterbatch:  171                                                       Stearic acid        2             Final                                       Sulfur              1.5           77-93° C.,                           Accelerator         1             40 RPM                                      Total Final:        175.5                                                     ______________________________________                                    

The compounded polymers were then cured using 1.5 inch×4 inch×0.040 inchtensile plaques, for 45 minutes at 300° F. (149° C.); Dynastat buttons,50 minutes at 300° F. (149° C.). The results of ensuing physical testsare reported in TABLE IV.

                                      TABLE IV                                    __________________________________________________________________________    PHYSICAL TESTS OF COMPOUNDED POLYMERS                                         OF EXAMPLES 1 AND 2                                                                         Wt %                                                                              1 Hz Dynastat                                                                          Ring Stress-Strain, psi.                           Example                                                                             ML/4/212                                                                              Bound                                                                             tan δ                                                                            RT                                                 No.   (gum)                                                                             (cpd)                                                                             Rubber                                                                            50° C.                                                                          M300                                                                              T.S.                                                                             % Eb                                        __________________________________________________________________________    1     32  81  28  0.110    2169                                                                              2836                                                                             419                                         2     33  84  ca.29                                                                             0.107    2177                                                                              2327                                                                             359                                         __________________________________________________________________________

The test results reported in TABLE IV, show that the compounded polymerof EXAMPLE 1 has a tan δ value about 30 percent below the value expectedfor an unmodified polymer of this molecular weight, prepared using atypical alkyllithium initiator. However, the polymer of EXAMPLE 2 failsto show any significant reduction in tan δ beyond this, despite itshaving been additionally treated at the tail with a reagent which isknown to be effective for reducing tan δ. The lack of additional effectwas also noted in the bound rubber results, where the result for EXAMPLE2 was not significantly different from that of EXAMPLE 1.

It was concluded that the polymer cement prepared in this manner,besides having somewhat broadened molecular weight distribution, alsodid not have sufficient live C-Li chain ends after polymerization toallow for significant reaction with a chain-end functionalizing reagent.Therefore, this method was not highly desirable for synthesis ofpolymers with optimum properties.

Experiment No. 2

Initiator Preparation

A second non-solubilized initiator was prepared. In a clean, stirred,one gallon stainless steel reactor, which had been dried andpreconditioned, and then nitrogen purged, was placed 1.22 pounds ofanhydrous hexanes, and 5.4 ml of a 0.77M solution of pyrrolidine inhexanes (4.16 meq). This was treated with 2.69 ml of a 1.58M solution ofn-butyllithium in hexanes (4.25 meq), stirring at room temperatureovernight. The resulting heterogeneous mixture was used in situ for thesubsequent polymerization.

Polymerization

The reactor containing the above initiator mixture was charged with 0.76pounds of a 34 weight percent blend of styrene and hexanes, 1.28 mmol ofTMEDA, and 3.06 pounds of a 25.5 weight percent blend of 1,3-butadienein hexanes. The reactor was heated to 46° C. and controlled at thattemperature for three hours.

A portion of the polymer cement made in this manner was transferred byneedle into three small bottles sealed as in Experiment 1 hereinabove.The remainder of the cement was collected in a large glass container,under a nitrogen purge. The cement in the large container, EXAMPLE 3 wasquenched by injection with 1.5 ml of isopropyl alcohol (i-PrOH), whilethe cement in the small bottles, EXAMPLE 4 was treated for an additional2 hours at 50° C. with 1.25 mol of 1,3-dimethylimidazolidin-2-one(1,3-DMI) per mol of lithium. The cement of EXAMPLE 4 was then quenchedwith 1.5 ml of i-PrOH, and both cement portions were treated with anantioxidant (2 ml of a mixture containing 2.0 wt. percent DBPC inhexane). The contents of the bottles were combined, and both EXAMPLES 3and 4 were coagulated separately in i-PrOH and drum dried. Suitablecharacterizations were performed, and the results are summarized inTABLE V hereinbelow.

Experiment No. 3

Repeat experiments were run using the same reactor as in Experiment No.2, employing the same amount of reagents, reaction times, andtemperatures from those of EXAMPLES 3 and 4. The resulting cement wascompounded in the recipe of TABLE III hereinabove, and is reported asEXAMPLE 5 hereinbelow. A portion of EXAMPLE 5 was end-linked by reactionwith one equivalent of SnCl₄ per equivalent of lithium, to produceEXAMPLE 6. A cement was also prepared as for EXAMPLE 5, except that theinitiator was allowed to form in the reactor for three (3) days insteadof overnight. Also, the resulting polymer was compounded in the recipeof TABLE VI hereinabove, and is reported herein as EXAMPLE 7. A portionof EXAMPLE 7 was treated with 1.25 mole of4-(N,N-dimethylamino)-benzylidene butylaniline per mole of lithium toproduce EXAMPLE 8. The order of addition of polymerization reagents forthe run producing EXAMPLE 7 and 8 were as follows: (1) TMEDA, (2)butadiene blend, (3) styrene blend. The polymeric products were workedup as described for EXAMPLES 3 and 4. Results of their characterizationand compounded evaluation are given in TABLE V hereinbelow.

The product polymers were cured using 1.5 inch×4 inch×0.040 tensileplaques, for 20 minutes at 165° C.; and Dynastat buttons, for 25 minutesand 165° C. TABLE V hereinbelow lists the characterizations andcompounded properties of Examples 5 to 8.

                  TABLE V                                                         ______________________________________                                        SUMMARY OF CHARACTERIZATION AND                                               COMPOUNDED PHYSICAL                                                           PROPERTIES OF EXAMPLES 3-8                                                                                                3,4,7,8                           Example No.                                                                             5      6      3    4    7    8    Control.sup.a                     ______________________________________                                        NMR                                                                           % VINYL.sup.b                                                                           52.9   52.9   70.0 70.0 63.6 63.6 ca.40                             % STY     22.4   22.4   22.0 22.0 26.6 26.6 ca.20                             DSC T.sub.g, °C..sup.c                                                           -42    -42    -24  -24  -24  -24  ca.-40                            GPC (THF)                                                                     M.sub.n × 10.sup.-3                                                               95.8   221    254  228  201  197  ca.200                            M.sub.w /M.sub.n                                                                        1.1    2.2    2.5  2.3  1.4  1.2  ca.24                             Coupling  --     78%    --   --   --   --   --                                ML/4/100° C.                                                           Raw       8      67     108  109  77   72   ca. 140                           Compound  34     71     94   101  72   75   74                                        TABLE NO.                                                             Test Recipe,                                                                            III    III    VI   VI   VI   VI   VI                                STRESS M300.sup.d                                                                       2116   2780   1361 1547 1520 1556 1276                              -STRAIN,  3115   2728   2373 2667 2649 2631 3551                              TB.sup.e                                                                      23° C. % EB.sup.f                                                                455    344    503  497  507  491  653                               % BOUND   21     37     34   40   27   37   32                                RUBBER.sup.g                                                                  DYNASTAT                                                                      1 HZ,                                                                         tan δ 50° C.                                                               0.144  0.078  0.156                                                                              0.138                                                                              0.162                                                                              0.143                                                                              0.186                             tan δ 23° C.                                                               0.167  0.109  0.180                                                                              0.219                                                                              0.231                                                                              0.219                                                                              0.227                             ______________________________________                                         .sup.a Blend of unmodified SBR's run in comparison with EXAMPLES 3, 4, 7,     8 in formulation of TABLE VI                                                  .sup.b Mol % of butadiene content as 1,2linkages                              .sup.c Onset of T.sub.g                                                       .sup.d Average ring stressstrain, 300% modulus, psi                           .sup.e Average ring stressstrain, tensile modulus, psi                        .sup.f Average percent elongation at break                                    .sup.g Weight percentage of rubber content in Cblack filled compound foun     insoluble in toluene after 2 days at room temperature, with no agitation 

                  TABLE VI                                                        ______________________________________                                        MEDIUM-OIL COMPOUNDING FORMULATION                                                                 Parts per                                                          Mix        Hundred                                                  Ingredient                                                                              Order      Parts Rubber                                             ______________________________________                                        Polymer   1          100        Masterbatch                                   Carbon black,                                                                           2          54         60 RPM                                        145-155° C.,                                                           ZnO       3          3                                                        Stearic acid                                                                            4          2                                                        Antioxidant                                                                             5          4.25                                                     Procesing aids                                                                Aromatic oil                                                                            6          27.6                                                     Total Masterbatch:                                                                             190.85                                                       Sulfur               2.25       Final                                         Accelerator          2.15       77-93° C.,                             blend                           40 RPM                                        Total Final:     195.25                                                       ______________________________________                                    

The results in TABLE V show the shortcomings of polymerization withN-lithiopyrrolidide initiators. Although the initiator/monomers chargedin runs 3,5 and 7 were the same (1.0 meq of lithium per 100 grams ofmonomer), the molecular weight of the products ranged from 96,000 to254,000, which is evidence of the highly erratic initiator. The highmolecular weight products are indicative of slow initiation relative topropagation, presumably due to the heterogenous nature of the system.EXAMPLE 5 exhibited a tan δ reduction at 50° C. about 31% lower thanthat of an unmodified polymer of similar microstructure and molecularweight. The result of end-linking of the live cement of EXAMPLE 5, viaSnCl₄, leading to EXAMPLE 6 was a further reduction in tan δ, to about40% of that of an unmodified polymer of the same base (uncoupled)molecular weight. The bound rubber content, which is indicative of theextent of interaction with carbon black, increased appreciably while theGPC showed that 78 percent of the polymer chains were end-linked, anindication that an appreciable fraction of "live" chain-ends were stillavailable for linking.

EXAMPLES 3, 4 and 7, 8 resulted in polymers of such high molecularweight that they were not processable for formulation in the low oilrecipe of TABLE III, but were formulated according to the recipe ofTABLE VI, which contains 27 parts per 100 rubber of oil for betterprocessing. The results of the evaluations in TABLE V indicate thatthese polymers show reduced tan δ, but the 13-16 percent reductionrelative to the unmodified SBR elastomers is small compared to thatdemonstrated in the EXAMPLES 5 and 6. Little change in viscosityoccurred upon attempting end-linking with SnCl₄, indicating that therewas little active C-Li remaining at the chain ends after polymerizationin these polymers. The SnCl₄ -treated polymers (EXAMPLES 4 and 8)exhibited tan δ's which were about 75 percent of that of the unmodifiedsamples.

In summary, the results of polymerizations which were initiated usingN-lithiopyrrolidide as described hereinabove, were highly erratic, bothwith respect to the nature and composition of the product as well as toother characteristics thereof.

II. Polymerization with a Solubilized Initiator

Experiment No. 4

Initiator Preparation

A dried, stainless steel one gallon reactor under a nitrogen atmosphere,was charged with 1.22 pounds of hexane, and then with 5.4 ml of 0.77Mpyrrolidine in hexane (4.16 meq) followed by 2.7 ml of 1.58Mn-butyllithium in hexane (4.27 meq). The mixture was stirred overnightat 90° F. (32° C.). The reactor was then charged with 90 grams of 25.4weight percent 1,3-butadiene in a hexane solution (423 mmol ofbutadiene), and the mixture was heated at 110° to 120° F. (43° to 49°C.) for one hour. This effectively places a SOL group on the pyrrolidinemoiety consisting on average of about 100 parts of 1,3-butadiene.

Polymerization

There was then charged to the reactor, 0.76 pounds of 33 weight percentstyrene in hexane, containing 1.06 mmol of TMEDA, followed immediatelyby 2.89 pounds of the 25.4 weight percent butadiene/hexane blend. Thisprovided for an initiator to monomer charged ratio of 1.0 meq of lithiumper 100 grams of monomer (1.0 meq Li phgm). The polymerization wasallowed to continue for 2 hours at 120° F. (49° C.) and the live cementwas collected through a twelve gauge stainless steel needle into foursmall beverage bottles, fitted and purged as described in the precedingexamples.

The cements in two of the bottles, EXAMPLE 9, were quenched by injectionwith 1.5 ml of i-PrOH, while the cements in the other two bottles,EXAMPLE 10, were treated for an additional two hours at 50° C. with 1.2mol of tributyltin chloride per mol of lithium. The cement of EXAMPLE 10was then quenched with 1.5 ml of i-PrOH, and both cement portions weretreated with an anti-oxidant as in Experiment III hereinabove. BothEXAMPLES 9 and 10 were coagulated separately in i-PrOH and drum dried.Suitable characterizations were performed, and the results aresummarized in TABLE VII hereinbelow.

Experiment No. 5

Initiator Preparation

A mixture of 25.1 meq of pyrrolidine and 25.1 meq of n-butyllithium inhexane was stirred under nitrogen over a weekend at room temperature.This was treated with 50.2 meq of THF in hexane, and the resultingmixture was used to initiate the polymerization.

Polymerization

A dried, stainless steel five gallon reactor under a nitrogenatmosphere, was charged with 8.53 pounds of hexane, 3.17 pounds of 33weight percent styrene in hexane, 8.78 mmol of TMEDA, followedimmediately by 17.89 pounds of a 25.4 weight percent butadiene/hexaneblend, and the initiator prepared hereinabove, contained 25.1 meq oflithium. The polymerization was run for 2.25 hours at 110° to 120° F.(43° to 49° C.) and the live cement was collected through a twelve gaugestainless steel needle into five small beverage bottles, fitted andpurged as described in the previous examples, and through a 1/2 inchpipe into two dried and purged large containers under a nitrogen purge.

The cements in the large containers, EXAMPLE 11, were quenched byinjection with i-PrOH, while the cements in the bottles, EXAMPLE 12,were treated first for an additional 0.5 hours at 50° C. with 0.3equivalents of tin tetrachloride per mol of lithium, followed bytreatment for 2 hours at 50° C. with 0.84 mols of1,3-dimethyl-2-imidazolidinone (1 ,3-DMI) per mol of lithium. The cementremaining in the reactor, EXAMPLE 13, was treated for about 2 hours at50° C. with 0.8 equivalents of SnCl₄ per equivalent of lithium. Thepolymeric products were worked up as described for EXAMPLES 9 and 10hereinabove. Results of their characterizations and compoundedevaluations are given in TABLE VII hereinbelow.

Experiment No. 6

Initiator Preparation

A separate portion of the same initiator used in EXAMPLES 11, 12 and 13was set aside and used two days later as follows, with an estimatedconcentration of 0.6 meq/ml.

Polymerization

The procedure used to polymerize the base cement of EXAMPLES 11-13 wasrepeated. The live product cement was collect through a twelve gaugestainless steel needle into five small beverage bottles, fitted andpurged as described in the preceding examples and through a 1/2inch pipeinto two dried and purged large containers under a nitrogen purge.

The cements in the large containers in EXAMPLE 14, were quenched byinjection with i-PrOH while the cements in the bottle, EXAMPLE 15, weretreated first for an additional 0.5 hours at 50° C. with 0.3 equivalentsof tin tetrachloride per mol of lithium, followed by treatment for 2hours at 50° C. with 0.85 mol of 1,3-DMI per mol of lithium. Thepolymeric products were worked up as described for EXAMPLES 9 and 10,results of their characterizations and compounded evaluations are givenin TABLE VII hereinbelow.

                  TABLE VII                                                       ______________________________________                                        SUMMARY OF CHARACTERIZATION AND                                               COMPOUNDED PHYSICAL PROPERTIES                                                OF EXAMPLES 9-15                                                              Example No. 9      10     11   12   13   14   15                              ______________________________________                                        NMR % VINYL.sup.b                                                                         42.7   42.7   53.3 53.3 53.3 50.1 50.1                            % STY       19.4   19.4   20.6 20.6 20.6 20.6 20.6                            DSC T.sub.g, °C..sup.c                                                             -45    -45    -38  -38  -38  -43  -43                             GPC (THF)                                                                     M.sub.n × 10.sup.-5                                                                 1.45   1.44   1.30 2.42 2.45 1.13 2.09                            M.sub.w /M.sub.n                                                                          1.15   1.17   1.14 1.79 2.09 1.15 1.94                            Coupling    --     --     --   53%  64%  --   54%                             ML/4/100° C.                                                           Raw         24     24     29   78   94   19   76                              Compound    70     90     82   103  114  76   107                             Test Recipe,                                                                              III    III    III  III  III  III  III                             TABLE NO.                                                                     STRESS-STRAIN                                                                             2125   2514   2177 2374 2903 2903 2706                            M300.sup.c                                                                    STRESS-STRAIN,                                                                            2832   3275   2982 2956 3445 3418 3451                            TB.sup.d                                                                      23° C. % EB.sup.e                                                                  419    409    431  403  387  395  409                             % BOUND     28.4   49.5   31.3 42.0 42.3 --.sup.g                                                                           --.sup.g                        RUBBER.sup.f                                                                  DYNASTAT 1 HZ,                                                                tan δ +50° C.                                                                0.079  0.056  0.080                                                                              0.076                                                                              0.078                                                                              0.129                                                                              0.103                           tan δ -20° C.                                                                0.374  0.389  0.675                                                                              0.684                                                                              0.431                                                                              0.541                                                                              0.563                           ______________________________________                                         .sup.a Mol % of butadiene content as 1,2linkages                              .sup.b Onset of T.sub.g                                                       .sup.c Average ring stressstrain, 300% modulus, psi                           .sup.d Average ring stressstrain, tensile modulus, psi                        .sup.e Average percent elongation at break                                    .sup.f Weight percentage of rubber content in Cblack filled compound foun     insoluble in toluene after 2 days at room temperature, with no agitation      .sup.g Not tested                                                        

Experiment No. 7

Initiator Preparation

A mixture of 28.6 meq of pyrrolidine, 57.2 mmol of THF, and 29.15 meq ofn-butylithium in hexane, was stirred under a nitrogen atmosphereovernight at room temperature. An aliquot from the resulting mixture(about 0.56 milliequivalent (meq) per ml) was used to initiate thepolymerization.

A five gallon stainless steel reactor was then charged with 6.42 poundsof hexane, 28.6 mol equivalent of the above 0.56M initiator, and 1.25pounds of a 24.2 weight percent blend of butadiene and hexane, and themixture was heated at 100° F. (35° C.) for one hour.

Polymerization

There was then charged to the reactor, 3.53 pounds of 34 weight percentstyrene in hexane, 9.7 mmol of TMEDA, and 17.85 pounds of thebutadiene/hexane blend. This provided for an initiator to monomer chargeratio of 1.05 meq Li phgm, and a monomer ratio of approximately 20weight percent styrene/80 weight percent butadiene. The polymerizationwas run for 1.75 hours at 110° to 115° F. (43° to 46° C.). The reactorwas finally charged with 0.3 pounds of the butadiene/hexane blend, and a4.1 pound sample of the cement was immediately collected in a largecontainer and quenched by adding i-PrOH, EXAMPLE 16. The contentsremaining in the reactor were treated by stirring with 22.2 ml of 1.0NSnCl₄ for 1.5 hours at 100° to 110° F. (43° to 46° C.), and the cementwas dropped under a nitrogen purge into a five gallon canistercontaining a small amount of i-PrOH EXAMPLE 17.

The cements from EXAMPLES 16 and 17 were treated with an antioxidant asin the immediately preceding experiment, and both samples werecoagulated in i-PrOH and drum dried. Suitable characterizations wereperformed and the results are summarized in TABLE VIII hereinbelow.

Experiment No. 8

Initiator Preparation

A mixture of 88.8 meq of pyrrolidine, 177.8 mmol of THF, and 89.8 meq ofn-butylithium in hexane was stirred under nitrogen overnight at roomtemperature. An aliquot from the resulting mixture (approximately 0.57meq per ml) was used to initiate polymerization.

A five gallon stainless steel reactor was then charged with 6.55 poundsof hexane, 47.1 ml (26.7 meq) of the above 0.57M initiator, and 1.0pound of a 24.2 weight percent blend of butadiene in hexane, and themixture was heated at 100° F. (38° C.) for 30 minutes.

Polymerization

There was then charged into the reactor, 4.41 pounds of 34 weightpercent styrene in hexane, 9.08 mmol of TMEDA, and 17.1 pounds of thebutadiene/hexane blend. This provided for an initiator to monomer chargeratio of 0.98 meq Li phgm, and a monomer ratio of approximately 25weight percent styrene/75 weight percent butadiene. The polymerizationwas run 2.3 hours at 110° to 115° F. (43° to 46° C.). The reactor wasfinally charged with 0.5 pounds of the butadiene/hexane blend, and a 3.5pound sample of the cement was immediately collected in a largecontainer and quenched by adding i-PrOH, EXAMPLE 18. The contentsremaining in the reactor were treated by stirring with 21.0 ml of 1.0NSnCl₄ at 115° F. (46° C.). After reaction, the cement was dropped undera nitrogen purge into a five gallon canister containing a small amountof i-PrOH, EXAMPLE 19. The cements were treated with an antioxidant asin the immediately preceding example and both cements from EXAMPLES 18and 19 were coagulated separately in i-PrOH and then drum dried.Suitable characterizations were performed and the results are summarizedin TABLE VIII hereinbelow.

                  TABLE VIII                                                      ______________________________________                                        SUMMARY OF CHARACTERIZATION AND                                               COMPOUNDED PHYSICAL PROPERTIES                                                OF EXAMPLES 16-19                                                             Example No.      16      17      18    19                                     ______________________________________                                        NMR % VINYL.sup.b                                                                              42.7    43.1    43.4  43.4                                   % STY            20.4    20.1    24.9  24.9                                   DSC T.sub.g, °C..sup.c                                                                  -47     -46     -45   -45                                    GPC (THF)                                                                     M.sub.n × 10.sup.-5                                                                      1.00    2.41    1.22  --                                     M.sub.w /M.sub.n 1.10    1.48    1.26  --                                     Coupling         --      86%     --    69%                                    ML/4/100° C.                                                           Raw              7       82      20    113                                    Compound         47      94      61    98                                     Test Recipe,     III     III     III   III                                    TABLE NO.                                                                     STRESS-STRAIN M300.sup.c                                                                       2165    2525    2643  2903                                   STRESS-STRAIN, TB.sup.d                                                                        3167    3452    3283  3714                                   23° C. % EB.sup.e                                                                       447     423     405   409                                    DYNASTAT 1 HZ,                                                                tan δ +50° C.                                                                     0.100   0.079   0.098 0.092                                  tan δ -20° C.                                                                     0.289   0.312   0.495 0.548                                  ______________________________________                                         .sup.a Mol % of butadiene content as 1,2linkages                              .sup.b Onset of T.sub.g                                                       .sup.c Ring stressstrain, 300% modulus, psi                                   .sup.d Ring stressstrain, tensile modulus, psi                                .sup.e % Elongation at break                                             

The product polymers were compounded and tested as indicated in the testrecipes show in TABLE III, and cured as above. TABLE VII lists thecharacterizations and properties of the polymers from EXAMPLES 9-15.TABLE VIII lists the characterizations and compounded properties ofEXAMPLES 16-19.

The results in TABLES VII and VIII show the advantages and the desirableresults obtained from polymerization with the initiators according tothe present invention. In contrast to the results in TABLE V, EXAMPLES9-19 demonstrate the consistency of diene polymerizations employingthese initiators. Namely, the polymerizations show relativelyreproducible and predictable molecular weights, with narrow molecularweight distributions, and the polymer cements exhibit better viabilityof the living C-Li chains for further reactions. The dicapped polymersof EXAMPLES 10, 12, 13 and 17 show exceptionally low hysteresis, atabout 40 percent to 50 percent of the values expected for comparableunmodified polymers of the same base molecular weight.

EXAMPLES 6, 10, 12, 13, 17 and 19 also exhibit the advantageouscombination of N-Li initiation and end-linking or termination with a tincompound, such as R₃ SnCl or SnCl₄.

The results of polymerizations which were initiated in acyclic alkanesolvents using the lithium pyrrolidide as described in the comparativeEXAMPLES 1-8, were highly erratic both with respect to the nature andcomposition of the products as well as their hysteresis behavior.However, when formulated as the N-lithiohydrocarbon amide withnear-equivalent amounts of polar ligand or with monomer extension, asexemplified hereinabove, reproducible polymerizations with goodmolecular weight control, narrow molecular weight distributions, andgood preservation of living C-Li ends for further reactions areachieved.

Experiment No. 9 PREPARATION OF POLYMER FROM C₁₂ H₂₄ NLi·2THF INITIATOR

Preparation of C₁₂ H₂₄ NLi·2THF initiator:

Dodecamethyleneimine ("DDMI") was vacuum distilled from calcium hydrideand transferred under nitrogen to a dried, nitrogen-purged bottle. TheN-lithio salt of DDMI was prepared by treating 10 ml of a 0.4M solutionof DDMI in hexanes with 2 ml of a 4.0M solution of THF in hexanes,followed by the slow addition of 2.35 ml of a 1.7M solution ofn-butyllithium in hexanes, with gentle swirling. Swirling was continuedat room temperature overnight. The resulting 0.28M solution was a clear,pale yellow. If the DDMI were treated by rapid addition ofn-butyllithium, or in the absence of at least about 2 equivalents of theTHF, cloudiness and/or precipitation occurred fight away. The C₁₂ H₂₄NLi·2THF solution was stable for at least several days at roomtemperature. Samples were drawn from it by syringe for use in initiatingpolymerization.

Polymerization of Butadiene and Styrene with C₁₂ H₂₄ NLi·2THF or n-BuLi:

A 0.28M solution of the above initiator was added to sealed bottlescontaining an 80%/20% by weight blend of butadiene and styrene inhexanes, at a level of 1.0 meq Li/100 grams monomer, andN,N,N',N-tetramethylethylenediamine ("TMEDA") was added at 0.45 TMEDA/Li(mol/mol). The mixtures were agitated at 50° C. for 2.5 hr, proceedingto approximately 90-100% conversion to polymer. In practice, there isconsiderable leeway in the reaction times and temperatures, much thesame as there is leeway in the reaction vessels, type of agitation,etc., used. The treated cements then were quenched by injection with 1ml of i-PrOH, treated with an antioxidant (3 ml of a mixture containing1.6 wt % DBPC in hexane), coagulated in i-PrOH, air-dried at roomtemperature, then drum-dried. Suitable characterizations were performed.Characterizations are summarized in Table IX. Table IX also containsdata for polymers prepared with n-butyllithium in the same way, in theabsence of DDMI or THF. These were prepared as a comparison, to show thetype of hysteresis behavior obtained in the absence of the initiatorcompositions of this invention. The relative hysteresis behavior istypical of that of nonfunctional polymers.

Polymerization of Butadiene and Styrene, and End-linking with SnCl₄ :

The above procedure was followed exactly, except that after 1.5 hour ofpolymerization at 50° C., the polymerization mixture was treated with0.8 equivalent of SnCl₄ per equivalent of Li charged. The products wereworked up in the same manner as above, and the characterizations arealso summarized in Table IX.

EVALUATION OF COMPOUNDED PROPERTIES

The product polymers were compounded and tested as indicated in the testrecipe shown in Table I and cured 20 minutes at 165° C. Results ofphysical tests are summarized in Table X. In addition, the carbon-boundrubber content of the uncured, final compounded stocks of Examples 1 and2 were 33 percent and 49 percent, respectively. This indicates anenhanced interaction between the polymer and carbon black in thesecases, compared to unmodified rubber, which typically exhibits less thanpercent carbon-bound rubber, and butyllithium-initiated, Sn-coupledrubber, which typically exhibits less than 35 percent carbon-boundrubber. The results of this test provided good evidence for reducedhysteresis in this polymer. The Dynastat tan δ (50° C.)=0.091-0.094 isabout 50 percent below the value expected for an unmodified polymer ofthis microstructure and molecular weight, such as would be preparedusing a typical alkyllithium initiator.

                                      TABLE IX                                    __________________________________________________________________________    CHARACTERIZATIONS OF POLYMERS FROM C.sub.12 H.sub.24 NLI.2THF INITIATORS      Example No.                                                                          Conditions T.sub.g, °C.                                                               % Sty                                                                             % 1,2                                                                             ML/4                                                                              M.sub.n                                                                           M.sub.w /M.sub.n                                                                  % Coupl                             __________________________________________________________________________    20     C.sub.12 H.sub.24 NLi.2THF                                                               -31.4                                                                             20.9                                                                              56.2                                                                              26.2                                                                              127724                                                                            1.25                                                                              (6% HMW)                                   50° C.                                                          21     C.sub.12 H.sub.24 NLi.2THF                                                               -34.4                                                                             21.0                                                                              53.7                                                                              86.1                                                                              215628                                                                            1.71                                                                              74                                         50° C. - SnCl.sub.4 -coupled                                    22     n-BuLi only, 50° C.                                                               -39.9                                                                             20.8                                                                              49.1                                                                              5.8  89631                                                                            1.17                                                                              --                                  23     n-BuLi only, 50° C.                                                               -38.2                                                                             20.6                                                                              50.2                                                                              65.9                                                                              217335                                                                            1.51                                                                              82                                         SnCl.sub.4 -coupled                                                    __________________________________________________________________________

                  TABLE X                                                         ______________________________________                                        COMPOUNDED EVALUATIONS OF                                                     POLYMERS PREPARED USING                                                       C.sub.12 H.sub.24 NLI.2THF INITIATOR                                                         %             Dis-                                             Exam- Tensile  Elong.        persion                                                                             %      Dynastat,                           ple   Strength,                                                                              at      ML/   Index,                                                                              Bound  1 Hz, tan                           No.   psi      break   4-Cpd %     Rubber δ, 50° C.              ______________________________________                                        20    3306     441     74    91    33.0   0.091                               21    3673     426     104   92    48.9   0.094                               22    2375     427     30    96    9.2    0.186                               23    3024     449     66    97    12.6   0.120                               ______________________________________                                    

A preferred method of preparing the initiators according to theinvention, will now be described. A vessel, such as a small bottlecontaining a Teflon or glass-clad magnetic stirring bar, is dried,sealed, and purged ,with nitrogen. The following is added by syringewhile stirring:

1. 30 mmol anhydrous 2° amine in hydrocarbon solvent, and

2. 60 mmol anhydrous polar solubilizer in hydrocarbon solvent.

3. 30.1 mmol of alkyl lithium in hydrocarbon solvent is added by syringeat once, with stirring, while taking precaution for back-pressures (thelarger ring amides may tend to precipitate if the alkyllithium is addedtoo rapidly).

The solution will heat and develop pressure immediately, but will soonbegin to cool back down. When larger amounts of reagent are prepared,e.g. 250-300 mmol in large bottles or 0.5-1.5 mol in reactors, bestresults are obtained when chilled or cold water cooling is used to keepthe peak temperature at about 38° C. or below. The normal procedure hasbeen to allow the mixture to stir overnight at room temperature beforeusing. However, the reaction is essentially complete within minutes. Themixture should be clear, straw-yellow, without significantprecipitation. Light-to-moderate haziness or cloudiness does not appearto affect activity. Anhydrous conditions are required. (SOL)/hydrocarbonsolvent solutions with less than 30 ppm of water give best results.Initiator reagents can be stored under positive nitrogen pressures forperiods of up to several weeks at room temperature (25°-27° C.).N-Lithio pyrrolidine·2THF solutions prepared and stored in this mannerat about 0.5M-1.5M in hexanes are stable for periods of about three tofour weeks, and are effective initiators for diene and/or vinylaromatic(co)polymerizations, giving polymers with excellent properties. N-Lithioperhydroazepine·2THF solutions prepared and stored in this manner atabout 0.3M-0.9M in hexanes are stable for at least several days, and canalso be used with good results in polymerizations.

It should now be clear from the foregoing examples and specificationdisclosure, that initiators according to the present invention areuseful for the anionic polymerization of diene monomers. Reproduciblepolymerization of such polymers within a relatively narrow molecularweight range is achieved, and the resulting polymers also exhibit goodpreservation of live C-Li ends, when compared to the nonsolubilizedinitiators heretofore known in the art.

It is to be understood that the invention is not limited to the specificinitiator reactants, monomers, terminators, polar coordinators orsolvents disclosed herein, except as otherwise stated in thespecification. Similarly, the examples have been provided merely todemonstrate practice of the subject invention and do not constitutelimitations of the invention. Those skilled in the art may readilyselect other monomers and process conditions, according to thedisclosure made hereinabove.

Thus, it is believed that any of the variables disclosed herein canreadily be determined and controlled without departing from the scope ofthe invention herein disclosed and described. Moreover, the scope of theinvention shall include all modifications and variations that fallwithin the scope of the attached claims.

What is claimed is:
 1. A functionalized polymer comprising:a polymerchain comprising at least one polymerization unit selected from thegroup consisting of conjugated dienes having from about 4 to about 12carbon atoms, monovinyl aromatic monomers having 8 to 18 carbon atomsand trienes, said polymer chain carrying at least one functional group Aselected from the group consisting of azacyclotridecane,azacycloheptadecane, 1-azacycloheptadec-9-ene, and,1-azacycloheptadec-8-ene, wherein A is derived from a polymerizationinitiator having the formula

    (A)Li(SOL).sub.y

where y is of from about 1 to about 3; and SOL is a solubilizingcomponent selected from the group consisting of hydrocarbons, ethers,amines and mixtures thereof.
 2. A functionalized polymer, as set forthin claim 1, prepared by the steps of forming a solution of one or moreanionically polymerizable monomers in an alkane solvent; and,polymerizing said monomers in the presence of said polymerizationinitiator.
 3. A functionalized polymer, as set forth in claim 2, whereinthe said polymer is multifunctional as a result of being further reactedwith a functional group of a compound selected from the group consistingof terminating agents, coupling agents and linking agents.
 4. Afunctionalized polymer, as set forth in claim 3, wherein saidterminating agent, coupling and linking agents are selected from thegroup consisting of carbon dioxide;N,N,N',N'-tetraalkyldiaminobenzophenones; N,N-dialkylaminobenzaldehydes;1,3-dialkylimidazolidinones; 1-alkyl substituted pyrrolidinones; 1-arylsubstituted pyrrolidinones; dialkyl- and dicycloalkylcarbodiimideshaving from about 5 to about 20 carbon atoms; (R₃)_(a) ZX_(b) ;##STR18## where Z is tin or silicon; R₃ is selected from the groupconsisting of alkyls having from about 1 to about 20 carbon atoms,cycloalkyls having from about 3 to about 20 carbon atoms, aryls havingfrom about 6 to about 20 carbon atoms and aralkyls having from about 7to about 20 carbon atoms; X is chlorine or bromine; a is from 0 to 3 andb is from about 1 to 4 where a+b=4; each R₄ is the same or different andis selected from the group consisting of alkyls, cycloalkyls and aryls,having from about 1 to about 12 carbon atoms; R₅ is selected from thegroup consisting of t-alkyls, phenyls, alkylphenyls andN,N-dialkylaminophenyls, having from about 4 to about 20 carbon atoms;each R₆ is the same or different, and is selected from the groupconsisting of alkyls and cycloalkyls having from about 1 to about 12carbon atoms; and, R₇ is selected from the group consisting of alkyls,phenyls, alkylphenyls and N,N-dialkylaminophenyls having from about 1 toabout 20 carbon atoms.
 5. A functionalizod polymer, as set forth inclaim 4, wherein the two R₆ groups together form a cyclic group.
 6. Avulcanizable elastomeric compound having reduced hysteresis propertiescomprising:an elastomeric polymer comprising at least one polymerizationunit selected from the group consisting of conjugated dienes having fromabout 4 to about 12 carbon atoms, monovinyl aromatic monomers having 8to 18 carbon atoms and trienes, said polymer having chains carrying thefunctional group A selected from the group consisting ofazacyclotridecane, azacycloheptadecane, 1-azacycloheptadec-9-ene, and,1-azacycloheptadec-8-ene, wherein A is derived from a polymerizationinitiator having the formula

    (A)Li(SOL).sub.y

where y is of from about 1 to about 3; and SOL is a solubilizingcomponent selected from the group consisting of hydrocarbons, ethers,amines and mixtures thereof and from about 5 to 80 parts by weight ofcarbon black, per 100 parts of said polymer.
 7. A tire having decreasedrolling resistance resulting from a treadstock containing a vulcanizableelastomeric compound as set forth in claim
 6. 8. A vulcanizable rubbercomposition comprising:a polymer comprising at least one polymerizationunit selected from the group consisting of conjugated dienes having fromabout 4 to about 12 carbon atoms, monovinyl aromatic monomers having 8to 18 carbon atoms and trienes, said polymer having chains carrying atleast one amine functional group A selected from the group consisting ofazacyclotridecane, azacycloheptadecane, 1-azacycloheptadec-9-ene, and,1-azacycloheptadec-8-ene; wherein A is derived from the reaction productof an organolithium compound and an amine; and a tin-carbon bond.
 9. Atire formed from the vulcanizable rubber composition of claim 8 and fromabout 5 to 80 parts by weight of carbon black, per 100 parts of saidpolymer.
 10. A rubber composition comprising:a polymer comprising atleast one polymerization unit selected from the group consisting ofconjugated dienes having from about 4 to about 12 carbon atoms,monovinyl aromatic monomers having 8 to 18 carbon atoms and trienes,said polymer having chains carrying at least one amine functional groupA selected from the group consisting of azacyclotridecane,azacycloheptadecane, 1-azacycloheptadec-9-ene, and,1-azacycloheptadec-8-ene, wherein A is derived from the reaction productof an organolithium compound and an amine; and a second functional groupselected from the group consisting of terminating agents, couplingagents and linking agents.
 11. A rubber composition as set forth inclaim 10, wherein said terminating agent, coupling and linking agentsare selected from the group consisting of carbon dioxide;N,N,N',N'-tetraalkyldiaminobenzophenones; N,N-dialkylaminobenzaldehydes;1,3-dialkyl-2-imidazolidinones; 1-alkyl substituted pyrrolidinones;1-aryl substituted pyrrolidinones; dialkyl- anddicycloalkyl-carbodiimides having from about 5 to about 20 carbon atoms;(R₃)_(a) ZX_(b) ; ##STR19## where Z is tin or silicon; R₃ is selectedfrom the group consisting of alkyls having from about 1 to about 20carbon atoms, cycloalkyls having from about 3 to about 20 carbon atoms,aryls having from about 6 to about 20 carbon atoms and aralkyls havingfrom about 7 to about 20 carbon atoms; X is chlorine or bromine; a isfrom 0 to about 3 and b is from about 1 to about 4 where a+b=4; each R₄is the same or different and is selected from the group consisting ofalkyls, cycloalkyls and aryls, having from about 1 to about 12 carbonatoms; R₅ is selected from the group consisting of t-alkyls, phenyls,alkylphenyls and N,N-dialkylaminophenyls, having from about 4 to about20 carbon atoms; each R₆ is the same or different, and is selected fromthe group consisting of alkyls and cycloalkyls having from about 1 toabout 12 carbon atoms; and, R₇ is selected from the group consisting ofalkyls, phenyls, alkylphenyls and N,N-dialkylaminophenyls having fromabout 1 to about 20 carbon atoms.
 12. A tire formed from the rubbercomposition of claim 10 and from about 5 to 80 parts by weight of carbonblack, per 100 parts of said polymer.